Introduce use counters for shadow DOM handling in plainText()

Source/core/editing/Editor.cpp

Index: Source/core/editing/Editor.cpp
diff --git a/Source/core/editing/Editor.cpp b/Source/core/editing/Editor.cpp
index b814c33d5d81c7d1dabbe42ac3fdfe2dfbf75a59..9b664e20be67749f7374149a821ec018cf0e2271 100644
--- a/Source/core/editing/Editor.cpp
+++ b/Source/core/editing/Editor.cpp
@@ -1145,7 +1145,7 @@ bool Editor::findString(const String& target, FindOptions options)
 {
     VisibleSelection selection = frame().selection().selection();
 
-    RefPtrWillBeRawPtr<Range> resultRange = rangeOfString(target, selection.firstRange().get(), options);
+    RefPtrWillBeRawPtr<Range> resultRange = rangeOfString(target, selection.firstRange().get(), static_cast<FindOptions>(options | FindAPICall));
 
     if (!resultRange)
         return false;